TWI618152B - Ammonia-containing plasma nitridation of a layer of a three-dimensional structure on a substrate - Google Patents

Abstract

Methods and apparatus for forming a nitrogen containing layer are provided herein. In some embodiments, the method includes placing a substrate onto a substrate support of a processing chamber, the substrate having a first layer disposed thereon; heating the substrate to a first temperature; and exposing the first layer to RF plasma, RF power the slurry is formed by comprising ammonia (NH ₃₎ a process gas to the nitrogen-containing layer is converted into the first layer, wherein less than about 8eV plasma ion energy.

Description

Ammonia-containing plasma nitridation of a layer of a three-dimensional structure on a substrate

Embodiments of the Invention The large system relates to semiconductor processing, and more particularly to methods of forming nitrogen-containing layers.

The scaling of semiconductor devices such as dynamic random access memory (DRAM), logic devices, etc. is limited by the gate leakage current (J _g ). For example, when the thickness of the gate dielectric layer is scaled, leakage may occur between the channel and the gate of the transistor device, causing device failure. Incorporating nitrogen into the gate dielectric layer reduces gate leakage current. For example, a gate dielectric layer at a 32 nm (nm) node can include bismuth oxynitride (SiON), where the presence of nitrogen can reduce gate leakage current in the device.

Typically, a plasma nitridation process is used to incorporate nitrogen into the gate dielectric layer. The plasma nitridation process reduces gate leakage current, but sacrifices other predetermined properties, such as flat band voltage (V _fb ), threshold voltage. (V _t ) and mobility. For example, increasing the nitrogen content in the gate dielectric will increase V _t inappropriate and excessive decrease in mobility. In addition, under typical processing conditions, oxygen diffuses from the gate dielectric layer, thereby further reducing device performance, such as reducing the dielectric properties of the gate dielectric layer.

Additionally, the dielectric layer on the nitrided semiconductor wafer for use in the semiconductor structure involves the addition of nitrogen to the planar semiconductor structure using plasma nitridation or thermal nitridation. However, the use of a 3-dimensional (3D) semiconductor structure such as a FinFET device requires that the nitride layer be wound around the 3D semiconductor structure, and the amount of nitrogen incorporated into the top surface of the 3D semiconductor structure is substantially equal to the amount of nitrogen incorporated under the sidewall of the 3D semiconductor structure, This is called conformality. The conformality can be calculated as the percentage of nitrogen falling along the depth below the sidewall of the 3D semiconductor structure.

A method of forming a nitride layer is thermal nitridation using ammonia (NH ₃ ). Although the use of ammonia (NH ₃₎ may be provided for proper thermal nitridation conformality, but this process can not provide a predetermined distribution of nitrogen in the top surface of the dielectric layer. Another method of forming a nitride layer is inductively coupled plasma nitridation using ions formed of nitrogen (N ₂ ). While this approach provides a predetermined nitrogen distribution within the dielectric film, the resulting conformality is not appropriate. While yet another far end plasma nitridation process can provide suitable conformality, this process requires temperatures in excess of about 600 ° C to about 1000 ° C to excessively and improperly thicken the oxide layer in the gate stack.

Accordingly, the present invention provides a method of forming a nitrogen-containing layer, and the nitrogen-containing layer has improved conformality.

Methods and apparatus for forming a nitrogen containing layer are provided herein. In some embodiments, the method includes placing a substrate onto a substrate support of a processing chamber, the substrate having a first layer disposed thereon; heating the substrate to a first temperature; and exposing the first layer to radio frequency (RF) plasma , is formed by the RF plasma containing ammonia (NH ₃₎ a process gas to the nitrogen-containing layer is converted into the first layer, wherein less than about 8eV plasma ion energy.

In some embodiments, a method of forming a nitrogen-containing layer includes placing a substrate onto a substrate support of a processing chamber, the substrate having a first layer disposed thereon, wherein the first layer is a 3-dimensional structure; and heating the substrate to a temperature of about 250 ° C a first temperature to about 500 ° C; and exposing the first layer to RF plasma, the RF plasma being formed from a process gas comprising ammonia (NH ₃ ) to convert the first layer into a nitrogen-containing layer, wherein the process gas ammonia (NH ₃₎ the total gas flow meter comprising from about 0.5% to about 99.5%, and the remainder being a rare gas, wherein plasma having an ion energy of less than about 8eV.

The above summary is not intended to limit the scope of the invention. Other and further embodiments of the invention are described below.

102, 104, 106 ‧ ‧ steps

110‧‧‧Method

200‧‧‧Semiconductor device

202‧‧‧Substrate

204‧‧‧ first floor

206‧‧‧ Plasma

208‧‧‧Nitrogen-containing layer

210‧‧‧ top surface

214‧‧‧ side wall

300‧‧‧reactor

304‧‧‧Power splitter

310‧‧‧ chamber

312‧‧‧Antenna

312 _A , 312 _B ‧‧‧ coil

314‧‧‧Substrate

316‧‧‧Support

317‧‧‧Clamping device

318‧‧‧RF power supply

319, 324‧‧‧ matching network

320‧‧‧ ceiling

321‧‧‧heater

322‧‧‧ bias source

323‧‧‧Lamps

325‧‧‧ feet

326‧‧‧ entrance

327‧‧‧Ion-free radical shielding

329‧‧‧ mouth

330‧‧‧ cavity wall

331‧‧‧ tablet

334‧‧‧Electrical grounding

336‧‧‧vacuum pump

338‧‧‧ gas panel

340‧‧‧ Controller

342‧‧‧ memory

344‧‧‧CPU

346‧‧‧Support circuit

348‧‧‧ gas source

349‧‧‧ catheter

350‧‧‧Gaseous mixture

355‧‧‧ Plasma

362‧‧‧ throttle valve

378, 380‧‧ ‧ treatment volume

402, 404‧‧‧ area

406‧‧‧ Grounding Grid

408‧‧‧ telescopic tube

410‧‧‧Sports components

412‧‧‧Power supply

416‧‧‧ surface

In order to make the above summary of the present invention more obvious and understood, the description may be made in conjunction with the reference embodiments. It is to be understood that the appended claims are not intended to

1 is a flow chart showing a method of forming a nitrogen-containing layer in accordance with some embodiments of the present invention.

2A through 2C illustrate stages in which a gate dielectric layer is fabricated in accordance with some embodiments of the present invention.

Figure 3 illustrates a suitable plasma nitriding reactor in accordance with some embodiments of the present invention.

Figure 4 illustrates a substrate support suitable for use in a plasma nitriding reactor, in accordance with some embodiments of the present invention.

To facilitate understanding, the same reference numerals are used to represent common elements in the figures. To simplify the description, the drawings are not drawn to scale. Reasonable The elements and features of an embodiment are advantageously incorporated in other embodiments and are not described herein.

Methods and apparatus for forming a nitrogen containing layer are provided herein. The method and apparatus of the present invention facilitates improved nitridation of a target layer (e.g., a first layer) by assisting in increasing nitrogen content, and improved oxygen retention at an interface between a target layer and another device layer (e.g., a polysilicon gate). . The method and apparatus of the present invention are also advantageous for improving the conformality of a nitride dielectric film on top of a 3D semiconductor structure.

FIG. 1 illustrates a method 110 for forming a nitrogen-containing layer, in accordance with some embodiments of the present invention. Generally, method 110 includes providing a partially fabricated semiconductor structure including a substrate having a first layer disposed thereon. The semiconductor structure can be a partially fabricated semiconductor structure such as a logic, DRAM or flash memory device. The nitrogen-containing layer formed by the process may be one or more gate dielectric layers, tunnel oxide layers, spacer layers, or semiconductor structures that benefit from nitridation such as reduced junction leakage current, gate leakage current, and the like. Any suitable layer.

The method 110 will fabricate a semiconductor structure description for the portions shown in FIGS. 2A to 2D, and FIGS. 2A to 2D respectively illustrate stages of fabricating a semiconductor structure including a first layer formed on a substrate. The method 110 can be carried out in any plasma reactor suitable for providing the low energy plasma, such as a reactor configured to provide inductive coupling or remote plasma. A plasma reactor embodiment suitable for use with the process of the present invention will be described later with reference to Figure 3. Plasma reactors can be used alone or more often as processing modules like integrated semiconductor substrate processing systems or clustering tools, such as CENTURA from Applied Materials, Inc., Santa Clara, California, USA. ^® DPN gate stacking integrates semiconductor wafer processing systems. Other tools are also available, including those from other manufacturers.

The method 110 begins at step 102 by providing a substrate 202, wherein as shown in FIG. 2A, the substrate 202 has a first layer 204 to be nitrided disposed thereon. The substrate 202 and the first layer 204 can be part of a fully or partially fabricated semiconductor device 200. The first layer 204 can be a 3-dimensional or 3D structure, or a portion of a 3D structure. Here, compared with the conventional 2D planar transistor, the conductive channel is mainly formed under the gate, and the 3-dimensional (or 3D) structure refers to a semiconductor structure in which the transistor forms a conductive path on three sides of the vertical structure. The substrate 202 can be of various sizes, such as wafers having a diameter of 200 millimeters (mm) or 300 mm and rectangular or square panels. Substrate 202 can comprise materials such as crystalline germanium (eg, Si<100> or Si<111>), germanium oxide, strained germanium, germanium, doped or undoped polysilicon, doped or undoped germanium wafers. , patterned or unpatterned insulating layer on silicon (SOI), carbon doped yttrium oxide, tantalum nitride, doped yttrium, lanthanum, gallium arsenide, glass, sapphire, and the like.

The semiconductor device 200 may be formed entirely or partially on the substrate 202 and includes at least a first layer 204 to be nitrided. The semiconductor device 200 (when completed) is, for example, a field effect transistor (FET), a dynamic random access memory (DRAM), a flash memory device, a 3D FinFET device, or the like. The first layer 204 can be used, for example, as a gate dielectric layer of a transistor device, a tunneling oxide layer of a flash memory device, a spacer layer on top of a gate structure, and a polysilicon dielectric layer (IPD) of a flash memory device. Wait. The first layer 204 can have any suitable thickness depending on the particular application in which the first layer 204 is employed. For example, the first layer 204 can have a thickness of from about 0.5 nanometers (nm) to about 10 nm. The first layer 204 may comprise an oxide layer such as hafnium oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), hafnium niobate (HfSiO _x ) or any other oxide layer suitable for semiconductor devices and to be nitrided. For example, in some embodiments, the oxide layer can be a native oxide layer, or can be formed by any suitable oxidation process, including the oxidation process described below. The first layer 204 is not necessarily limited to an oxide layer, and other suitable layers also benefit from the inventive methods described herein. For example, other suitable embodiments of the first layer 204 can include other suitable semiconductor materials such as germanium (Si), germanium (Ge), germanium (SiGe), tantalum carbide (SiC), III-V compounds, or metals. , metal nitride or metal oxide, such as tungsten (W), titanium (Ti), tantalum (Ta), titanium nitride (TiN), tantalum nitride (TaN), titanium oxide (TiO ₂ ) or aluminum oxide (Al ₂ O ₃ ) and so on. The first layer 204 can also be a layer stack, such as a first sub-layer of SiO _{2 and a} second sub-layer of HfO ₂ , or a first sub-layer of SiO _{2 and a} second sub-layer of HfSiO _{x ,} and the like.

Next, in step 104, the substrate 202 is heated before and during nitridation. Heating the substrate 202 helps provide more nitrogen content into the first layer 204 and improves device properties. For example, heating the substrate 202 to a temperature of at least about 250 ° C or at least about 350 ° C helps to increase the nitrogen content in the first layer 204 (eg, an atomic percent content of from about 5 to about 35). In some embodiments, the substrate can be heated from about 250 ° C to about 550 ° C, or in some embodiments from about 350 ° C to about 450 ° C. In some embodiments, the substrate can be heated to about 400 °C. The actual maximum substrate temperature may depend on the hardware limitations and/or the thermal budget of the substrate to be processed.

In embodiments of the first layer 204 oxide layer, increasing the temperature facilitates self-chromatization of less oxygen (e.g., less than about 20%), thereby reducing oxygen concentration at the interface of the first layer 204 and the substrate 202. In some embodiments, substrate 202 is heated to between about 250 ° C and about 550 ° C. In some embodiments, the first layer 204 is an oxide layer and the substrate 202 can be heated up to about 300 ° C to about 550 ° C, or about 350 °C to about 500 °C.

In some embodiments, the substrate 202 is located in the reactor to maximize heat transfer to the substrate, such as heat transfer between the substrate 202 and the substrate support, during which the substrate support is placed on the substrate 202. As such, the substrate 202 can be secured to the substrate support using a clamping device, such as an electrostatic chuck (ESC), vacuum chuck, or other suitable device. Clamping the substrate 202 facilitates reproducible heat transfer even at low pressures (process pressure zones), for example, at about 4 mTorr to about 1 Torr, or at about 10 to about 80 mTorr, at about 10 to about 40 mTorr, or about 10 to about 20 mTorr. Optionally, in embodiments in which the electrostatic chuck is configured to secure the substrate 202, a second plasma can be formed over the substrate 202 to help stabilize the substrate temperature when the substrate is held. For example, the second plasma may be formed of a non-reactive gas including at least one of argon (Ar), helium (He), krypton (Kr), xenon (Xe), etc. to preheat the substrate 202, thus clamping the substrate 202 to After the substrate support and the extinguishing of the plasma, the substrate 202 does not undergo a sharp temperature change, resulting in process variation and/or wafer damage. Here, the non-reactive gas includes a gas that does not substantially react with the substrate (eg, does not substantially deposit on or etch the substrate).

The substrate 202 can be heated by any suitable heating mechanism that can increase and maintain the substrate temperature at about 250 ° C or above, or in some embodiments, about 350 ° C or above. Suitable heating mechanisms include resistance heating, radiant heating, and the like. For example, as described in the following embodiments of reactor 300, one or more electrical resistance heaters can be provided on the substrate support to provide substrate 202 heat. Alternatively, the substrate may be heated by one or more lamps or other sources of energy, such as disposed above and/or below substrate 202.

In a heating mode, the heating element is embedded in the electrostatic chuck to directly heat the substrate by the electrostatic chuck. This method has several advantages: (1) the substrate can be maintained at a constant temperature during the entire process, even if the process pressure is as low as 4 mTorr; (2) due to strict control of the substrate temperature during the process, Therefore, the processing results of each substrate (nitrogen dose and nitrogen incorporation mass percentage (N%)) can be reproduced; and (3) the heating uniformity pattern in the heating element of the electrostatic chuck is carefully designed, or individual control is provided The multi-zone heating element can change (e.g., compensate) the pattern of nitride uniformity within the substrate.

In the case of an electrostatic chuck heater, the substrate temperature will rise rapidly due to the nature of the clamping/heating process, for example up to about 30 ° C / sec. At such high heating rates, it may not be possible to heat each part of the wafer at the same rate, so the temperature difference within the substrate at some point may reach an extreme value (eg >75 ° C), causing the substrate (eg semiconductor wafer) to rupture . To avoid breakage, a preheat step can be performed before the substrate is clamped. The preheating step can include flowing a non-reactive gas, such as nitrogen (N ₂ ) or helium, at a rate of from about 400 sccm to about 4 liters per minute at a pressure of about 1-10 Torr (eg, about 8 Torr). He), etc., for about 20 to about 60 seconds or more (for example, about 50 seconds) while maintaining the electrostatic chuck heater at a predetermined temperature (for example, about 400 ° C), and the substrate is placed on the surface of the electrostatic chuck, but not Being clamped. The preheating step helps to bring the substrate temperature close to the electrostatic chuck temperature (eg, within about 150 °C of the substrate target temperature) prior to clamping, thereby reducing the potential thermal shock to the substrate when the substrate is held. In some embodiments, the backside gas can be used to preheat the wafer when a low contact electrostatic chuck (eg, an electrostatic chuck having a contact area of up to about 5%) is used to support the substrate. In some embodiments, the substrate can be preheated prior to delivery to the processing chamber, for example, using a contact or non-contact (eg, luminaire) method.

Depending on the situation, the processing chamber can be preconditioned prior to nitriding the first layer 204 to reduce residual oxygen levels in the processing volume. For example, residual oxygen levels such as water vapor, water (H ₂ O), etc. can cause substrate 202 or first layer 204 to be improperly parasiticly oxidized. To avoid this, the interior of the processing chamber (including the lid, side walls, and pedestal or chuck) can be preconditioned with a preconditioned slurry formed from a preconditioned gas. The preconditioned gas may, for example, include nitrogen (N ₂ ), ammonia (NH ₃ ), or ammonia (NH ₃ ) and an inert gas (such as argon (Ar)), or any chamber suitable for reducing water vapor content and aging (season) Part of the gas and / or gas composition. In some embodiments, the preconditioned gas consists of or consists essentially of nitrogen (N ₂ ) or ammonia (NH ₃ ), or ammonia (NH ₃ ) and an inert gas (eg, argon (Ar)). In some embodiments, the pre-conditioning can be performed before or during clamping (eg, securing the substrate to the chuck). In some embodiments, the pre-conditioning can be performed prior to heating the substrate or prior to nitriding the first layer 204.

Next, at step 106, first layer 204 is exposed to a radio frequency (RF) formed by a process of plasma gas, a process gas comprising or substantially consisting of ammonia, or (NH ₃₎ components. In some embodiments, the first layer 204 is exposed to RF plasma while maintaining the processing chamber from about 5 mTorr to about 500 mTorr, or from about 10 mTorr to about 80 mTorr, or A pressure of from about 10 mTorr to about 40 mTorr, or from about 10 mTorr to about 20 mTorr, is formed to form a nitrogen-containing layer 208, as shown in Figure 2C. For example, in some embodiments, the process gas is a mixture of rare gases may be pure ammonia (NH ₃₎ or ammonia (NH _3). The rare gas is, for example, argon (Ar). In some embodiments, the process gas comprises ammonia (NH ₃ ) and argon (Ar). In some embodiments, the process gas consists solely of ammonia and argon. In some embodiments, the process gas consists essentially or consists essentially of ammonia and argon.

In some embodiments, the process gas may be supplied at a total gas flow rate of from about 100 sccm to about 1000 sccm or about 400 sccm, although other flow rates may be employed depending on the application and process chamber configuration. In some embodiments, the process gas comprising from about 10% to 100% NH ₃ (e.g., NH ₃ flow rate of about 10-1000sccm), for the remainder essentially rare gas such as argon (Ar) (e.g., rare gas percentage It is from about 0% to about 90%). In some embodiments, the process gas comprising from about 0.5% to 99% NH ₃ (e.g., NH ₃ flow rate of about 0.5-990sccm), for the remainder essentially rare gas such as argon (Ar) (e.g., rare gas percentage It is from about 1% to about 99.5%). In some embodiments, the process gas is about 1.5% to 50% NH ₃ (e.g., NH ₃ flow rate of about 15-500sccm), for the remainder essentially rare gas such as argon (Ar) (e.g., a noble gas percentage It is from about 50% to about 98.5%). In some embodiments, the process gas comprises from about 10% to about 99% of a rare gas (eg, a rare gas flow of from about 100 to 990 sccm). In some embodiments, the process gas comprises from about 80% to about 99% of a rare gas (eg, a rare gas flow of from about 800 to 990 sccm).

The process gas can be introduced into a plasma reactor, such as plasma reactor 300, and used to form plasma 206. In some embodiments, the plasma density is from about 10 ¹⁰ to about 10 ¹² ions per cubic centimeter. The plasma 206 can be formed using RF source power. In some embodiments, the plasma energy that forms the plasma 206 is less than 8 electron volts (eV). In some embodiments, the plasma energy that forms the plasma 206 is less than 4 eV. In some embodiments, the ion energy that forms the plasma 206 is from about 1 eV to about 4 eV. In some embodiments, the RF source power can produce up to about 2500 watts or more. The RF source power can be provided at any suitable RF frequency. For example, in some embodiments, the RF source power can be provided at a frequency of about 2 to about 60 megahertz (MHz), such as 13.56 MHz.

The plasma 206 can be pulsed or continuously applied at an effective power of up to about 1000 watts. For example, the plasma 206 can be applied continuously at up to about 400 watts for a period of from about 10 to about 400 seconds or about 100 seconds. The time (eg, shortened) can be adjusted to limit damage to the semiconductor device 200. Alternatively, the plasma 206 can be pulsed at a pulse frequency of about 4 kilohertz (kHz) to about 15 kHz. The pulsed plasma can have a duty cycle of from about 2% to about 30% at peak powers up to 2500 watts, wherein the duty cycle and/or RF source power can be adjusted to limit damage to the semiconductor device 200. In some embodiments, the plasma 206 can be generated with up to 20% duty cycle pulses at peak powers up to 2000 watts. In some embodiments, the plasma 206 can be generated with a duty cycle pulse of between about 5% and about 10% at a peak power of up to 2000 watts.

The present inventors found having low ion energy (e.g., ion energy less than 8eV) and using a plasma composed of radicals NH * 206 essence ammonia from ammonia (NH ₃₎ or diluted in a rare gas (NH ₃₎ consisting of The process gas facilitates more conformal nitridation of the first layer 204, such as a hafnium oxide (HfO ₂ ) layer, such that the amount of nitrogen incorporated into the top surface 210 of the nitrogen-containing layer 208 is substantially equal to the sidewall 214 incorporated into the nitrogen-containing layer 208. The amount of nitrogen.

In the formation of the low ion energy plasma 206, the use of pure or diluted ammonia gas (NH ₃ ) such as argon is superior to the typical nitridation process because ammonia (NH ₃ ) forms NH radicals in the plasma 206. Will not be affected by the field across the plasma sheath. As such, the NH radicals will reach the substrate 202 without any preferred orientation and react with any of the oriented substrate surfaces, such as the top surface 210 and sidewalls 214 of the first layer 204, to conformally nitride the first layer 204. , will not improperly thicken the first layer 204.

In some embodiments, the exposed surface of the substrate 202 at least partially covers an upper sacrificial layer (not shown), such as a mask layer, from exposure to the plasma 206 (eg, limiting plasma exposure to the substrate 202 and/or the first layer 204) Scheduled part). In some embodiments, during exposure of the first layer 204 to the plasma 206, the pressure within the plasma reactor can be as high as about 80 mTorr, about 10 mTorr to about 80 mTorr, about 10 mTorr to About 40 mTorr, or about 10 mTorr to about 30 mTorr.

The nitrogen-containing layer 208 formed by exposing the first layer 204 to the plasma 206 can be used, for example, as a gate dielectric layer of the transistor device, a tunneling oxide layer of the flash memory device, and a spacer layer on the top of the gate structure. , polycrystalline dielectric layer (IPD) of a flash memory device, and the like. The nitrogen containing layer 208 can have a thickness of from about 0.3 nm to about 10 nm. Nitrogen containing layer 208 can have a nitrogen content of from about 3 atomic percent to about 25 atomic percent. The nitrogen-containing layer 208 may comprise an oxynitride layer such as yttrium oxide (SiON), hafnium oxynitride (HfON), hafnium lanthanum hydride (HfSiON) or any other oxynitride layer suitable for semiconductor devices and to be nitrided. The nitrogen-containing layer 208 is not necessarily limited to the nitrogen oxide layer, and other suitable layers also benefit from the inventive methods described herein. For example, in other suitable embodiments, the nitrogen-containing layer 208 can include or be substituted with a SiCN or other germanium-containing (Si) compound, a metal-containing compound, such as titanium oxide or titanium nitride, hafnium oxide or tantalum nitride, aluminum oxide, or Aluminum nitride, etc.

After the formation of the nitrogen-containing layer 208, the method 110 is substantially complete, and an additional processing step (not shown) can be performed to complete the fabrication of the semiconductor device 200 and/or other devices (not shown) on the substrate 202.

The process of the invention (e.g., process 110) can be carried out in a plasma reactor. For example, Figure 3 illustrates a schematic of a plasma reactor 300 suitable for practicing the embodiments of the present invention. Reactor 300 can be used alone or more often as a processing module that integrates a semiconductor substrate processing system or cluster tool, such as CENTURA ^® DPN gate stack integrated semiconductor crystal from Applied Materials, Inc., Santa Clara, California, USA. Round processing system.

Reactor 300 includes a processing chamber 310 having a substrate support 316 disposed within a conductive body (cavity wall) 330 and a controller 340. In some embodiments, the substrate support (cathode) 316 is coupled to the bias supply 322 via a first matching network 324. Bias source 322 typically produces a source of up to 500 W at a frequency of about 13.56 MHz, which can produce continuous or pulsed power. In other embodiments, source 322 can be a direct current (DC) or pulsed DC source. In some embodiments, no bias power is provided.

In some embodiments, the processing chamber 310 includes a liner (not shown) to line the inner surface of the processing chamber 310. In some embodiments, the liner is cooled, for example, by a coolant flow passage that is disposed within the liner for coolant flow. In some embodiments, the processing chamber 310 (and other components exposed to the plasma during processing) is coated with a plasma resistant material. For example, in some embodiments, the processing chamber 310 can be coated with a material that is resistant to plasma attack. In some embodiments, the coating may comprise a quartz or ceramic material, such as a yttria (Y ₂ O ₃ ) based ceramic composition, alumina, or the like. In accordance with embodiments of the present invention, it is advantageous to reduce hydrogen radical attack to chamber components during the process while helping to maintain the rate of nitridation.

The chamber 310 can be fitted with a substantially planar dielectric ceiling 320. Other modifications of the chamber 310 may have other types of ceilings, such as dome-shaped or other shaped ceilings. At least one inductive coil antenna 312 is disposed above the ceiling 320 (as shown in FIG. 3 is a dual coaxial antenna 312 including an outer coil 312 _A and an inner coil 312 _B ). Each antenna 312 is coupled to an RF power source 318 via a second matching network 319. RF source 318 typically produces up to about 5000 W at an adjustable frequency of 2 MHz to 13.56 MHz and can produce continuous or pulsed plasma. Typically, cavity wall 330 can be coupled to electrical ground 334.

In some embodiments, the power splitter 304 is disposed in the bushing to couple the outer coil 312 _A and the inner coil 312 _B with the RF power source 318. Power splitter 304 can be used to control the amount of RF power provided to each antenna coil (and thereby assist in controlling the plasma characteristics of the corresponding internal and external coil regions). The dual coil antenna configuration facilitates improved nitrogen dose control in each region (e.g., to the first layer 204) as in the method 110 described above.

Any and/or two antennas 312 may be tilted and/or raised/lower relative to ceiling 320, as appropriate. Changing the position and/or angle of the antenna 312 can be used, for example, to change the characteristics of the plasma formed within the processing chamber, such as uniformity.

Additionally, as the case may be, a plasma shield/filter may be placed over the substrate support to improve nitridation control, such as the first layer 204, in the method 110 described above. The plasma shield/filter may comprise a material, such as quartz, and may be grounded to the chamber 310 to remove ionic species in the plasma formed in the processing chamber. For example, an ion-radical shield 327 can be disposed over the substrate support 316 within the chamber 310. Ion-radical shield 327 is electrically isolated from chamber wall 330 and substrate support 316 and typically includes a substantially flat plate 331 having a plurality of apertures 329. In the embodiment shown in FIG. 3, the ion-radical shield 327 is supported by a plurality of legs 325 above the susceptor within the chamber 310. Mouth hole 329 is away The surface of the sub-radical shield 327 defines a predetermined open area to control the plasma formed from the upper processing volume 378 of the processing chamber 310 to the lower processing volume 380 between the ion-radical shield 327 and the substrate 314. the amount. The larger the open area, the more ions pass through the ion-radical shield 327. The size and distribution of the apertures 329 and the thickness of the plate 331 will control the ion density in the volume 380. It is a shielded 327 series ion filter. An example of a suitable shield that would benefit from the present invention is described in U.S. Patent No. U.S. Patent Application Serial No., entitled "METHOD AND APPARATUS FOR PHOTOMASK PLASMA ETCHING", filed on June 30, 2004 by Kumar et al. Application No. 10/882,084. By varying the ion density near the surface of the wafer, the ion/free radical ratio can be controlled to control the nitridation distribution.

In some embodiments, the substrate support 316 includes a clamping device 317 to secure the substrate 314 to the support base during processing. For example, the clamping device 317 can include an electrostatic chuck or a vacuum chuck. The clamping device 317 helps to improve heat transfer between the substrate 314 and one or more of the resistive heaters 321 which are disposed on the substrate support 316. As described, one or more resistive heaters 321 can be disposed on the substrate support 316 and generally below the location of the substrate 314, and configured as a plurality of regions to assist in controlling the heated substrate 314. In some embodiments, the substrate support 316 includes an electrostatic chuck and also includes one or more electrical resistance heaters disposed within or under the electrostatic chuck. In some embodiments, the substrate support 316 does not include an electrostatic chuck, but has one or more resistive heaters disposed adjacent the support surface of the substrate support. In this embodiment, the substrate support with the electric resistance heater has a surface coating such as an aluminum nitride (for example, the substrate support may be made of aluminum nitride or have an aluminum nitride outer coating or the like).

In some embodiments, as shown in FIG. 4, the substrate support 316 does not have an electrostatic chuck, but includes an electrical resistance heater. The substrate support 316 shown in FIG. 4 includes a resistive heater 321 configured to adjust the temperature of the substrate 314. The heater 321 may include one or more regions (the outer region 402 and the inner region 404 shown in FIG. 4). Heater 321 is coupled to power source 412 and is capable of maintaining substrate 314 at temperatures up to about 500 °C. In some embodiments, the ground grid 406 is placed between the one or more heaters 321 and the upper surface 416 of the substrate support 316 to prevent the substrate 314 from adhering to the surface 416 of the substrate support 316. The inert coating described above can also be applied to the surface 416 of the substrate support 316.

In the case of an electrostatic chuck with a heater, the nitrogen dose and N% (eg, the mass percentage of nitrogen incorporated into the first layer 204 to form the nitrogen-containing layer 208) is proportional to the wafer temperature during the plasma process. . Therefore, in order to control and/or adjust the nitrogen dose and the N% uniformity on the wafer, two methods can be adopted: (1) heating the fixed area with the heating element in a pre-designed power density pattern to make the temperature of the wafer uniform The pattern is compensated for the plasma uniformity pattern; or (2) the adjustable power source is used to adjust the wafer by heating the multiple regions in different heating regions (usually center and edge dual regions, but more regions are also available) Temperature uniformity compensates for plasma uniformity patterns. In either mode, the temperature can be used as a knob to achieve the goal of improving nitridation uniformity within the wafer and/or to provide a predetermined nitrogen dose pattern in the substrate. In some embodiments, the nitrogen dose pattern is substantially uniform (eg, within about 1%).

The motion assembly 410 can be configured to control the height of the substrate support 316 to control the height of the substrate 314 during processing. The motion assembly 410 is intimately coupled to the chamber body 330 by an elastic bellows 408. Alternatively or in addition, the motion component 410 It is configurable to rotate the substrate support 316.

Referring back to FIG. 3, or in addition, one or more sources of radiation (eg, luminaire 323) may be provided to heat the substrate 314. The luminaire 323 can be configured similar to a radiant luminaire for a rapid thermal processing chamber. Other heating methods or designs can also be employed, including heating the substrate from above.

The temperature of the substrate 314 can be controlled by stabilizing the temperature of the substrate support 316. The heat transfer gas from the gas source 348 is supplied to the flow path and support surface formed on the back surface of the substrate 314 and/or the grooves (not shown) in the holding device 317 via the gas conduit. The heat transfer gas is used to promote heat transfer between the substrate support 316 and the substrate 314. During processing, the substrate support 316 can be heated by one or more resistive heaters 321 to a steady state temperature, and then the heat transfer gas assists in uniformly heating the substrate 314. With this thermal control, substrate 314 can be maintained at a temperature of from about 0 °C to about 550 °C.

In some embodiments, the substrate support 316 has, for example, a low thermal mass to prevent thermal shock from impinging on the substrate die. For example, the substrate support 316 can be configured to have no heat sink or a cooling plate coupled thereto to limit the rate of heat dissipation from the substrate support 316.

During typical operation, substrate 314 (eg, substrate 202) can be placed on substrate support 316, process gas is supplied from gas panel 338 via inlet 326, and the inlet is disposed on ceiling 320 and over the center of substrate 314. In some embodiments, the gas panel 338 is configured to supply process gas, such as ammonia (NH ₃₎ or hydrogen (H _2). The process gas may be combined with an additional gas, such as nitrogen (N ₂ ), helium (He), or argon (Ar), and flow into chamber 310 via inlet 326. The inlet 326 includes, for example, a baffle or similar gas inlet device to provide process gas perpendicular to the substrate 314 and radially forward into the processing chamber 310. After entering the processing chamber 310 via the inlet 326, the process gas forms a gaseous mixture 350. Power is applied from RF source 318 to antenna 312 to ignite gaseous mixture 350 into plasma 355 in chamber 310. Power may also be supplied from the bias source 322 to the substrate support 316, as the case may be. The pressure inside the chamber 310 is controlled by the throttle valve 362 and the vacuum pump 336. The temperature of the chamber wall 330 is controlled by a liquid containing conduit (not shown) that extends through the chamber wall 330.

The controller 340 includes a central processing unit (CPU) 344, a memory 342, and a CPU 344 support circuit 346, and assists in controlling the components of the nitridation processing chamber 310 and the nitridation process as described herein. Controller 340 can be any type of general purpose computer processor that can be used in industrial settings to control various chambers and sub-processors. The memory or computer readable medium 342 of the CPU 344 can be one or more readily available memories, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other. Type of local or remote digital storage. The support circuit 346 is coupled to the CPU 344 to support the processor in a conventional manner. These circuits include cache memory, power supplies, clock circuits, input/output circuits, and subsystems. The method of the present invention can be stored in memory 342 as a software routine and performed or motivated in the manner described above. The software routine can also be stored and/or executed by a second CPU (not shown) that is remote from the hardware controlled by the CPU 344.

Therefore, methods and apparatus for forming a nitrogen-containing layer are provided herein. The method and apparatus of the present invention facilitates improving the nitridation of a target layer (e.g., the first layer) by assisting in increasing the nitrogen content and reducing layer thickening, and improving the interface between the target layer and another device layer (e.g., a polysilicon gate). Oxygen retention.

While the above is directed to embodiments of the present invention, other and further embodiments of the present invention can be practiced without departing from the scope of the invention.

Claims (12)

A method of forming a nitrogen-containing layer, the method comprising the steps of: placing a substrate on a substrate support of a processing chamber, the substrate having a first layer disposed thereon, wherein the first layer is a 3 Dimensional structure; heating the substrate to a first temperature of from about 250 ° C to about 500 ° C; and exposing the first layer to an RF plasma formed from a process gas comprising ammonia (NH ₃ ) Converting the first layer to the nitrogen-containing layer, wherein the process gas comprises from about 0.5% to about 99.5% ammonia (NH ₃ ) as a total gas flow meter, and the remainder is a noble gas And wherein the RF plasma has an ion energy of less than about 8 eV, and wherein the amount of nitrogen in which a top surface of the nitrogen-containing layer is incorporated is substantially equal to the amount of nitrogen below a sidewall of the nitrogen-containing layer. The method of claim 1 wherein the RF plasma has an ion energy of less than about 4 eV. The method of claim 1 wherein the noble gas system is argon. The method of claim 1, wherein the flow rate of the ammonia (NH ₃ ) is from about 15 sccm to about 500 sccm. The method of claim 1 further comprising the step of exposing the first layer to the RF plasma while maintaining the processing chamber at a pressure of between about 5 mTorr and about 500 mTorr. The method of claim 1, further comprising the step of forming the RF plasma using a pulsed RF power source having a frequency of about 13.56 MHz. The method of claim 6 wherein the pulsed RF power supply supplies a power of up to 2000 watts and is powered up to a duty cycle of up to 30%. The method of claim 6 wherein the pulsed RF power source is powered during a duty cycle of from about 5% to about 10%. The method of claim 1 wherein the first layer comprises a semiconductor material, a metal or a metal oxide. The method of claim 9, wherein the first layer is germanium (Si), germanium (Ge), germanium (SiGe) or a III-V compound. The method of claim 9, wherein the first layer is tungsten (W), titanium (Ti), titanium nitride (TiN), tantalum (Ta) or tantalum nitride (TaN). The method of claim 9, wherein the first layer is titanium dioxide (TiO ₂ ) or aluminum oxide (Al ₂ O ₃ ).